Wreckerman's M927A3 cargo/tractor truck

[srodocker]

Maybe put some 1600s to try and level out the trailer?

 

[wreckerman893]

Maybe put some 1600s to try and level out the trailer?

The picture is somewhat deceiving. The truck is on an incline with the rear wheels in a small depression. It actually rides fairly level when it's on level ground. You can't put larger tires on the trailer due to clearance issues.

 

[Castle Bravo]

Thats actually really cool.

 

[Bighurt]

The picture is somewhat deceiving. The truck is on an incline with the rear wheels in a small depression. It actually rides fairly level when it's on level ground. You can't put larger tires on the trailer due to clearance issues.

I was going to suggest using a double oscillating fifth wheel off a 931 or 933 but I suspected some terrain deception.

 

[wheelspinner]

Its like a "B" train I see in Canada all the time, but I still think eventually you will be happier sliding the tandems back. The spring board effect from the weight behind the tandems won't be obvious until the least opportune time for it to rear its ugly head. I know you are an experienced operator, much beyond me, just looking at it analytically. I am just thinking of how my trucks have behaved with long rear overhanging loads.

 

[DUECE-COUPE]

Don't forget to mount a spare tire on the spare tire rack on the truck. I put it there for a reason!!!!

 

[Robo McDuff]

Looking at pics 2 and 3, this shouts for an air-lifted trailing third axle. What I mean is cut a normal spring off just behind the middle where the wheel is. Fix the front of the spring as close as possible without interfering with the tandem. Then put air bellows-springs on the backward end. Choose springs so that when not inflated, the bellows pull the trailing axle of the ground. When loaded and pulling a trailer, inflate the bellows enough to compensate for the trailer. Make sure that the bellows can even be inflated further. If needed, you then can inflate the bellows to max (never during driving) resulting in raising the normal wheels above the ground. Works like an air-jack. Great for changing tires or get out of the mud. Also covers the rear-collision bar and looks great.

 

[wreckerman893]

Robo......if this is a permanent mod that is exactly what I have in mind.

If there were enough room and if I had the skills I'd use a steering axle and have it turn like a HETT or PLS.

I don't think there is enough room for a set of front springs to go back there so it would have to be an air bag suspension with a raise and lower capabilitry. I would not use a live axle to save weight.

 

[Wildchild467]

Need to move the tandems back where they should be, similar to how a M819 is set up. I would use that as a guide to set your wheelbase... if you go forward with this project.

 

[wreckerman893]

Need to move the tandems back where they should be, similar to how a M819 is set up. I would use that as a guide to set your wheelbase... if you go forward with this project.

I measured the outside to outside distance on the front spring hanger today and there is sufficient room to mount an axle back there.

After looking at the number of airlines and electrical wiring that would have to be relocated to move the tandems back I figure it would be easier to install a third axle than move the axles.

The plus is that I have access to a set of front springs and both a pull or steering axle.

Here's a technical question for those fabrication gurus. What would be involved in making the rear axle steer. The donor truck still has all of the steering gear so when I pull the axle out I could probably get almost everything I need to do the installation.

 

[rebelqwes87]

Here's a technical question for those fabrication gurus. What would be involved in making the rear axle steer. The donor truck still has all of the steering gear so when I pull the axle out I could probably get almost everything I need to do the installation.

I would imagine the only option would be hydraulic steering. Either by separate controls or an orbital valve running off of you front steering. I'm no expert, just my $.02

Edit: And on a side note, I love watching somebody try something different.

 

[466Navastar]

a steering tag axle mounted behind the tandems would be pretty trick - especially if it could be raised and lowered as required like a m920

I suspect if you mounted the new rear steering axle and set the caster angle somewhere around the same as the front steering axle and put a decent size hydraulic damper on the tie rod - the new axle would just follow the truck....without scrubbing the tires and stressing the frame.

being your application is low usage and Im sure you desire low buck investment - why not just move the tandems back ?.....I saw one of those m927 or 928s somewhere on the internet a while ago - the owner moved the tandems back and it looked really nice. Ill look for the pic and let you know if I find it.

--------------------

took a look -I don't know if this is the one but it does illustrate what the truck looks like stretched.....http://www.ccsurplus.com/truck/379

 

[wreckerman893]

why not just move the tandems back ?

Because (whinny little beotch voice) I want something different.

a steering tag axle mounted behind the tandems would be pretty trick - especially if it could be raised and lowered as required like a m920

One thought would be to put slightly smaller tires on the axle and it would only contact the road if there was a heavy load on it. I've seen straight log trucks do this.

Another idea would be to make it a live axle by installing a jackshaft from the third axle to the added axle.

 

[466Navastar]

I didn't quite lol - but smiled at your reply....smiles are good.

 

[wreckerman893]

Today is fit and finish day. I completed
bolting the 5th wheel onto the plate and the plate to the frame.
Then I did some wire brushing and painting.
I also secured the IV cable and air lines so they will move with the trailer when it turns.
The rest of the day will be devoted to connecting the tail lights and brake lights on the bed to the existing wiring harness of the M927.
Pictures of the painted addition.

 

[guns1977]

I would imagine the only option would be hydraulic steering. Either by separate controls or an orbital valve running off of you front steering. I'm no expert, just my $.02

Edit: And on a side note, I love watching somebody try something different.

Hey wreckerman contact black creek productions armor, he is a hyd genius.

 

[wreckerman893]

I took it out on a shakedown cruise this afternoon and it pulls great, much better than looking back and seeing that wagon wiggling around behind me. The only issue I have is under certain conditions the trailer will get into the tailgate slightly. One more inch back and everything would have been gravy but in order to use the existing mounting holes on the M927 frame I had to set the 5th wheel there.
If I sell the bed that's on it I may lose the spare tire rack and install a custom flatbed or an ISO bed if I can find one.
Or I may re-install the stock bed and call it good.

 

[Tinydragon2001]

Mount the steer axle on the rear with the steering cylinder on the passenger side. Power the axle, plumb the cylinder to counter steer the front axle, and it'll look just like a HET...

 

[wreckerman893]

Mount the steer axle on the rear with the steering cylinder on the passenger side. Power the axle, plumb the cylinder to counter steer the front axle, and it'll look just like a HET...

I noticed the steering cylinder sits above the frame so it would interfere with a bed unless I raise the height of the bed (thus raising the center of gravity of an already tall truck).
The fluid lines would have to be plumbed all the way back to the rear steering cylinder. Prob be better to run hard lines most of the way.
For every action there is a reaction.
I could put a HEMMT cab on it and have a PLS truck. Note to self.....HEMMT's ride like an oxcart.

 

[Trailboss]

...I suspect if you mounted the new rear steering axle and set the caster angle somewhere around the same as the front steering axle and put a decent size hydraulic damper on the tie rod - the new axle would just follow the truck....without scrubbing the tires and stressing the frame....

I also thought free-steering front axle would turn as needed to follow the truck in turns, the same as the front axle on a truck that was being flat-towed. You might want the ability to lock the axle straight or lift the axle so it wont go catawampus when backing. Having said that, one problem I see with a free-steering axle is that it may accentuate the push-steering action of the trailer on the truck during turns or evasive maneuvers when a Prius cuts you off.

The potential push-steering action of the trailer may also be the greatest drawback of putting the 5-th wheel behind the rear axles since the leverage increases. I wouldn't apply brakes in a curve at speed, if at all possible, meaning brake as needed prior to entering the curve.